1. Field of the Invention
The present invention relates generally to a pulse generator, and more particularly to an adjustable, high current, high voltage pulse generator.
2. Description of the Background Art
Pulse generators are electronic devices that create electronic pulse train signals, such as a square wave signal. A pulse train may be used for a variety of things, such as feedback and control of motors, electronic displays, etc. In addition, a pulse train may be used in communication applications or for testing of devices, such as semi-conductor devices, wherein a load on the device may be varied by modifying the characteristics of a pulse train.
The pulse train may need to be provided with a variety of characteristics. Some of the characteristics that may need to be adjusted and controlled are the pulse rate/frequency, the pulse position, the pulse width, the pulse duty cycle, the voltage and current drive levels etc. Therefore, there is a large need for pulse generators that are controllable, flexible, and able to provide a high voltage and a high current output.
In the prior art, a pulse generator is typically a dedicated device, and may include an oscillator, amplifiers, and wave shaping circuitry. A pulse generator in the prior art generally provides a fixed voltage and current pulse train capability (such devices are relatively inexpensive and simple).
However, a pulse generator according to the prior art has several drawbacks. Because prior art pulse generators are usually designed for a specific purpose or application, they generally do not provide a flexible output timing, current, and/or voltage characteristics. The prior art devices that can provide a varying signal, such as a common lab-type pulse generator, have a limited accuracy and limited voltage and current drive capacities. For example, a prior art pulse generator typically must be amplified. Prior art pulse generators are therefore limited in the maximum amount of current they can supply under load during the switching or pulsing of the output supply. The prior art pulse generators are not able to adjust the regulated output voltage under pulse conditions.
There remains a need in the art, therefore, for a pulse generator having a high voltage output and high current output, but that can be accurately controlled and adjusted.
A controllable pulse generator is provided according to one embodiment of the invention. The pulse generator comprises a pulse generator device capable of generating to an external device under operation a pulse train output of a predetermined current level and of a predetermined voltage level according to one or more pulse train signals. The pulse generator further comprises a controller device communicating with the pulse generator device. The controller device is capable of accepting one or more pulse train requests and accepting one or more external signals and outputting the one or more pulse train signals in response. The controller device comprises a communication interface capable of communicating with one or more external devices and receiving the one or more pulse train requests. The controller device further comprises an oscillator that generates a precision reference waveform and a power supply that provides electrical power. The controller device further comprises a processor communicating with the communication interface. The processor executes a control routine, receives the precision reference waveform from the oscillator, receives the one or more pulse train requests from the communication interface, and generates one or more pulse train commands in response to the one or more pulse train requests. The controller device further comprises a trigger device capable of providing a trigger signal to the external device under operation. The controller device further comprises an output interface capable of relaying the one or more pulse train signals to the pulse generator device. The controller device further comprises a signal interface including at least one signal port for receiving one or more external signals. The controller device further comprises a signal processor that communicates with the processor and receiving the one or more pulse train commands. The signal processor also communicates with the signal interface and receives one or more external signals. The signal processor generates and transmits the one or more pulse train signals to the output interface. The output interface transmits the one or more pulse train signals to the pulse generator device.
A controllable pulse generator is provided according to one embodiment of the invention. The pulse generator comprises a controller device capable of accepting one or more pulse train requests and accepting one or more external signals and outputting one or more pulse train signals in response. The pulse generator further comprises a pulse generator device communicating with the controller device and receiving the one or more pulse train signals. The pulse generator device is capable of generating a pulse train output of a predetermined current level and of a predetermined voltage level according to the one or more pulse train signals. The pulse generator device comprises a first load resistor that is connected to a DC supply node and to a first load resistor node. The pulse generator device further comprises a second load resistor that is connected to a first pass-through node and to a second load resistor node. The pulse generator device further comprises a third load resistor that is connected to an output node and to a voltage divider node. The pulse generator device further comprises a fourth load resistor that is connected to the voltage divider node and to a ground node. The pulse generator device further comprises a first pass-through MOSFET that includes an input that is connected to the first load resistor node, an output connected to the first pass-through node, and a bias input that is connected to a hot swap node. The first pass-through MOSFET buffers a current supplied at the first load resistor node. The pulse generator device further comprises a second pass-through MOSFET that includes an input that is connected to a nine volt regulator input node, an output connected to a fourth pass-through node, and a bias input that is connected to a third pass-through node. The second pass-through MOSFET used as a voltage interlock buffers a current supplied at the nine volt regulator input node. The pulse generator device further comprises a third pass-through MOSFET that includes an input that is connected to the second load resistor node, an output connected to a second pass-through node, and a bias input that is connected to an adjustable voltage output node. The third pass-through MOSFET buffering a current supplied at the second load resistor node. The pulse generator device further comprises a first voltage doubler that includes inputs connected to the DC supply node and the ground node. The first voltage doubler increases an input DC voltage level. The pulse generator device further comprises a second voltage doubler that includes inputs connected to the nine volt regulator input node and the ground node and an output that is connected to an eighteen volt output node. The second voltage doubler increases an input DC voltage level. The pulse generator device further comprises a third voltage doubler that includes inputs connected to the adjustable positive voltage output node and the ground node and an output that is connected to the nine volt regulator input node. The third voltage doubler increases an input DC voltage level. The pulse generator device further comprises a hot swap controller that includes inputs that are connected to the DC supply node, to the first load resistor node, and to the ground node, and an output that is connected to the hot swap node. The hot swap controller senses a current in the first load resistor and provides a zero voltage output if no load exists across the first load resistor. The pulse generator device further comprises a transient voltage suppressor connected across the DC supply node and the ground node. The pulse generator device further comprises a first precision op amp that includes inputs that are connected to the first pass-through node and the second load resistor node and a reference voltage is received from a nine volt node. The first precision op amp receives voltages across a second load resistor and provides a current monitor output. The current monitor output provides a current measurement related to a current level in the second load resistor. The pulse generator device further comprises a MOSFET power switch that includes an input that is connected to the second pass-through node, an output that is connected to the output node, and a control input that is connected to a power switch input node. The MOSFET power switch is capable of being turned off and on in order to create a pulse train output. The pulse generator device further comprises a MOSFET switch driver that includes an input that is connected to an isolator output node, an output that is connected to the power switch input node, and a bias input that is connected to the third pass-through node. The MOSFET switch driver controls the MOSFET power switch in response to the one or more pulse train signals from the controller device. The pulse generator device further comprises a manual voltage adjustment device capable of generating a variable voltage level in response to a user input. The pulse generator device further comprises an adjustable positive voltage regulator that includes an input that is connected to the second load resistor node, an output that is connected to the adjustable voltage output node, and a control input that is connected to the adjustable voltage input node and to the manual (or programmed control) voltage adjustment device. The adjustable positive voltage regulator receives a doubled voltage supply and the variable voltage level from the manual voltage adjustment device and provides a manually adjusted voltage level to the MOSFET power switch. The pulse generator device further comprises a digital optical isolator that is connected to the fourth pass-through node, to the isolator output node, and to the pulse input port. The digital optical isolator receives a nine volt regulated DC input and a pulse train signal from a pulse input port and gates the nine volt regulated DC input according to the pulse train signal. The pulse generator device further comprises a voltage divider connected across the output node and the ground node of the pulse generator device. The voltage divider comprises a third load resistor connected to the output node and to a voltage divider node. The voltage divider further comprises a fourth load resistor connected to the voltage divider node and to the ground node. The pulse generator device further comprises a second precision op amp that is connected to the voltage divider node and the ground node. The second precision op amp receives an eighteen volt regulated input and a divided output voltage input from the voltage divider node and outputs a voltage measurement signal at a voltage monitor port. The voltage measurement signal is related to an output voltage of the pulse generator device at the output node.
A method for providing an adjustable, high voltage, high current pulse train output is provided according to yet another embodiment of the invention. The method comprises the steps of receiving in a controller device one or more pulse train requests from an external device and receiving one or more external signals. The method further comprises the step of generating in the controller device one or more pulse train signals in response to the one or more pulse train requests and the one or more external signals. The method further comprises the step of transmitting the one or more pulse train signals to a pulse generator. The method further comprises the step of generating in the pulse generator a high voltage, high current pulse train output corresponding to the one or more pulse train signals.